ABO ADVANCED FORMULAS PRACTICE
EXAMINATION 2026 QUESTIONS
WITH ANSWERS GRADED A+
◍ Forward Type.
Answer: Looking for unknown antigen on RBC, use known antibody
(Antisera), Agglutination indicates the presence of antigen, determines the
ABO group
◍ Which of the following shows ABO frequencies from most common to least
common?a. A > O > AB > Bb. AB > A > B > Oc. B > AB > A > Od. A > B
> AB > Oe. O > A > B > AB.
Answer: e. O > A > B > AB
◍ What antibody class are ABO antibodies primarily?a.IgAb.IgEc.IgGd.IgM.
Answer: IgM
◍ All of the following (a-d) would be classified as natural occurring antibodies
(produced from “look alike antigens” in the environment and not from
foreign red blood cell exposure)
except:a.Anti-Ab.Anti-Bc.Anti-A,Bd.Anti-De.All of the above (a-d) would
be classified as natural occurring antibodies.
Answer: Anti-D
◍ Which of the following would be considered
Codominant?a.AOb.ABc.A1A2d.Dd.
Answer: AB
◍ Which would be considered a heterozygous expression?a.OOb.eec.cEd.Cc.
Answer: Cc
◍ Reverse Type.
, Answer: Use Known antigen (reagent red cells) to detect--Unknown
antibody in plasma, agglutination indicates the presence of antibody,
confirms the ABO group (most of the time, ~2% discrepancy)
◍ Which one of the following is considered recessive?a.A1b.A2c.cd.Se.
Answer: A2
◍ ABO subgroups: "A" main subgroups.
Answer: Type "A" may be broken down into 2 main subgroups: A1 and A2
◍ 3+ agglutination appears as:a.One large solid agglutinate with a clear
backgroundb.Very fine agglutinates with a red backgroundc.Several large
clumps with a clear backgroundd.Several small-medium sized agglutinates
with a clear backgrounde.Complete hemolysis is seen (with no agglutinates).
Answer: Several large clumps with a clear background
◍ What % of A people have an unexpected reverse reaction that doesn't match
forward reaction.
Answer: 1% of the 40% that are type A
◍ A1 phenotype has which antigens.
Answer: A1 and A (H)
◍ A2 phenotype has which antigens.
Answer: A only (NO such thing as A2 antigen) (H)
◍ 1+ agglutination appears as:a.One large solid agglutinate with a clear
backgroundb.Very fine agglutinates with a red backgroundc.Several large
clumps with a clear backgroundd.Several small-medium sized agglutinates
with a clear backgrounde.Complete hemolysis is seen (with no agglutinates).
Answer: Very fine agglutinates with a red background
◍ If the Father's type (phenotype) was AB and the Mother's type was B, what
would be the possible genotypes of their offspring? (Not including any
subgroups).a.AA, AO, BB, BOb.AB, AA, BB, AOc.AB, AO, BB, BOd.AO,
AA, BO, OO.
Answer: AB, AO, BB, BO
EXAMINATION 2026 QUESTIONS
WITH ANSWERS GRADED A+
◍ Forward Type.
Answer: Looking for unknown antigen on RBC, use known antibody
(Antisera), Agglutination indicates the presence of antigen, determines the
ABO group
◍ Which of the following shows ABO frequencies from most common to least
common?a. A > O > AB > Bb. AB > A > B > Oc. B > AB > A > Od. A > B
> AB > Oe. O > A > B > AB.
Answer: e. O > A > B > AB
◍ What antibody class are ABO antibodies primarily?a.IgAb.IgEc.IgGd.IgM.
Answer: IgM
◍ All of the following (a-d) would be classified as natural occurring antibodies
(produced from “look alike antigens” in the environment and not from
foreign red blood cell exposure)
except:a.Anti-Ab.Anti-Bc.Anti-A,Bd.Anti-De.All of the above (a-d) would
be classified as natural occurring antibodies.
Answer: Anti-D
◍ Which of the following would be considered
Codominant?a.AOb.ABc.A1A2d.Dd.
Answer: AB
◍ Which would be considered a heterozygous expression?a.OOb.eec.cEd.Cc.
Answer: Cc
◍ Reverse Type.
, Answer: Use Known antigen (reagent red cells) to detect--Unknown
antibody in plasma, agglutination indicates the presence of antibody,
confirms the ABO group (most of the time, ~2% discrepancy)
◍ Which one of the following is considered recessive?a.A1b.A2c.cd.Se.
Answer: A2
◍ ABO subgroups: "A" main subgroups.
Answer: Type "A" may be broken down into 2 main subgroups: A1 and A2
◍ 3+ agglutination appears as:a.One large solid agglutinate with a clear
backgroundb.Very fine agglutinates with a red backgroundc.Several large
clumps with a clear backgroundd.Several small-medium sized agglutinates
with a clear backgrounde.Complete hemolysis is seen (with no agglutinates).
Answer: Several large clumps with a clear background
◍ What % of A people have an unexpected reverse reaction that doesn't match
forward reaction.
Answer: 1% of the 40% that are type A
◍ A1 phenotype has which antigens.
Answer: A1 and A (H)
◍ A2 phenotype has which antigens.
Answer: A only (NO such thing as A2 antigen) (H)
◍ 1+ agglutination appears as:a.One large solid agglutinate with a clear
backgroundb.Very fine agglutinates with a red backgroundc.Several large
clumps with a clear backgroundd.Several small-medium sized agglutinates
with a clear backgrounde.Complete hemolysis is seen (with no agglutinates).
Answer: Very fine agglutinates with a red background
◍ If the Father's type (phenotype) was AB and the Mother's type was B, what
would be the possible genotypes of their offspring? (Not including any
subgroups).a.AA, AO, BB, BOb.AB, AA, BB, AOc.AB, AO, BB, BOd.AO,
AA, BO, OO.
Answer: AB, AO, BB, BO
